U.S. patent number 11,432,922 [Application Number 17/517,027] was granted by the patent office on 2022-09-06 for biomaterial based on aligned fibers, arranged in a gradient interface, with mechanical reinforcement for tracheal regeneration and repair.
This patent grant is currently assigned to The Children's Mercy Hospital, The University of Kansas. The grantee listed for this patent is The Children's Mercy Hospital, The University of Kansas. Invention is credited to Michael Detamore, Lindsey Ott, Robert Weatherly.
United States Patent |
11,432,922 |
Detamore , et al. |
September 6, 2022 |
Biomaterial based on aligned fibers, arranged in a gradient
interface, with mechanical reinforcement for tracheal regeneration
and repair
Abstract
An implant can include a plurality of polymeric fibers
associated together into a fibrous body. The fibrous body is
capable of being shaped to fit a tracheal defect and capable of
being secured in place by suture or by bioadhesive. The fibrous
body can have aligned fibers (e.g., circumferentially aligned) or
unaligned fibers. The fibrous body can be electrospun. The fibrous
body can have a first characteristic in a first gradient
distribution across at least a portion of the fibrous body. The
fibrous body can include one or more structural reinforcing
members, such as ribbon structural reinforcing members, which can
be embedded in the plurality of fibers. The fibrous body can
include one or more structural reinforcing members bonded to the
fibers with liquid polymer as an adhesive, the liquid polymer
having a substantially similar composition of the fibers.
Inventors: |
Detamore; Michael (Lawrence,
KS), Ott; Lindsey (Lawrence, KS), Weatherly; Robert
(Overland Park, KS) |
Applicant: |
Name |
City |
State |
Country |
Type |
The University of Kansas
The Children's Mercy Hospital |
Lawrence
Kansas City |
KS
MO |
US
US |
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Assignee: |
The University of Kansas
(Lawrence, KS)
The Children's Mercy Hospital (Kansas City, MO)
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Family
ID: |
1000006545880 |
Appl.
No.: |
17/517,027 |
Filed: |
November 2, 2021 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20220054255 A1 |
Feb 24, 2022 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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16570510 |
Sep 13, 2019 |
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14239049 |
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PCT/US2012/050974 |
Aug 15, 2012 |
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61523894 |
Aug 16, 2011 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61L
27/10 (20130101); A61L 27/18 (20130101); A61L
27/14 (20130101); A61F 2/04 (20130101); A61F
2/20 (20130101); A61L 27/34 (20130101); A61L
27/34 (20130101); C08L 67/04 (20130101); A61L
27/18 (20130101); C08L 67/04 (20130101); A61L
2430/22 (20130101); A61L 2420/04 (20130101); A61L
2300/414 (20130101); A61L 2420/08 (20130101); A61F
2002/046 (20130101); A61F 2250/0018 (20130101); A61F
2250/0028 (20130101); A61F 2210/0076 (20130101) |
Current International
Class: |
A61F
2/04 (20130101); A61L 27/18 (20060101); A61L
27/34 (20060101); A61L 27/10 (20060101); A61F
2/20 (20060101); A61F 2/07 (20130101); A61F
2/06 (20130101); A61L 27/14 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2001212246 |
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Aug 2001 |
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JP |
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2013025819 |
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Feb 2013 |
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WO |
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Other References
International Search Report and Written Opinion for
PCT/US2012/050974 dated Feb. 28, 2013. cited by applicant .
Cheng et al. "Engineering the Microstruccture of Electrospun
Fibrous Scaffolds by Microtopography" 2013, BioMacromolecules
14:1349-1360. cited by applicant .
Liu et al. "Electrospun Fibrous Mats on Lithographically
Micropatterned Collectors to Control Cellular Behaviors" 2012,
Langmuir 28:17134-17142. cited by applicant .
Nanofiber Solutions, LLC v. Acera Surgical, Inc., IPR2021-01016,
Petition (PTAB May 28, 2021). cited by applicant.
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Primary Examiner: Mathew; Seema
Attorney, Agent or Firm: DLA Piper LLP (US)
Government Interests
GOVERNMENT RIGHTS
This invention was made with government support under NSF 0847759
awarded by the National Science Foundation. The government has
certain rights in the invention.
Parent Case Text
CROSS-REFERENCE
This patent application is a continuation of U.S. patent
application Ser. No. 16/570,510, filed Sep. 13, 2019, which is a
continuation of U.S. patent application Ser. No. 14/239,049, filed
Jan. 5, 2015, which is a U.S. national stage filing under 35 U.S.C.
.sctn. 371 of International Application No. PCT/US2012/050974,
filed Aug. 15, 2012, entitled "Fibrous Tracheal Patch," which
claims the benefit of U.S. Provisional Application Ser. No.
61/523,894, filed on Aug. 16, 2011. The contents of each of these
applications are hereby incorporated by reference in their
entireties.
Claims
The invention claimed is:
1. A fibrous scaffold consisting of: a layer comprising: a first
type of polymeric electrospun fiber; and a second type of polymeric
electrospun fiber; wherein at least one of the first type of
polymeric electrospun fiber and the second type of polymeric
electrospun fiber comprise a polymer selected from the group
consisting of polyglycolic acid, polylactic acid,
poly(lactic-co-glycolic acid), poly(L-lactide-co-caprolactone), and
polycaprolactone; and wherein the first type of polymeric
electrospun fiber and the second type of polymeric electrospun
fiber are co-electrospun; wherein the first type of polymeric
electrospun fiber and the second type of polymeric electrospun
fiber are randomly oriented; wherein the fibrous scaffold has a
shape selected from the group consisting of a patch and a
sheet.
2. The fibrous scaffold of claim 1, wherein the first type of
polymeric electrospun fiber comprises polyglycolic acid, and
wherein the second type of polymeric electrospun fiber comprises
poly(L-lactide-co-caprolactone).
3. The fibrous scaffold of claim 1, wherein the first type of
polymeric electrospun fiber comprises poly(lactic-co-glycolic
acid), and wherein the second type of polymeric electrospun fiber
comprises a biodegradable polymer.
4. The fibrous scaffold of claim 1, wherein the first type of
polymeric electrospun fiber comprises polycaprolactone, and wherein
the second type of polymeric electrospun fiber comprises
poly(lactic-co-glycolic acid).
5. The fibrous scaffold of claim 1, wherein the fibrous scaffold is
configured for use with a wound.
6. The fibrous scaffold of claim 1, wherein at least one of the
first type of polymeric electrospun fiber and the second type of
polymer electrospun fiber further comprise an active agent.
7. The fibrous scaffold of claim 6, wherein the active agent is
selected from the group consisting of an antimicrobial, a
pharmaceutical, a tissue growth factor, a protein, a nanophase
material, and combinations thereof.
8. The fibrous scaffold of claim 1, wherein the first type of
polymeric electrospun fiber comprises a first active agent, and
wherein the second type of polymeric electrospun fiber comprises a
second active agent different from the first active agent.
9. The fibrous scaffold of claim 1, further comprising a plurality
of live cells.
Description
BACKGROUND
Tracheal repair procedures date back to the late 19th century.
However, a predictably effective treatment is not available to
restore normal function to a stenotic (e.g., abnormal narrowing)
trachea without the use of an autologous tissue graft, which
results in the sacrifice of native tissue. Even with the use of an
autologous graft, the size, shape, and stiffness of the graft is
often not ideal. Countless tissue engineering and regenerative
medicine studies have attempted to regenerate tracheal tissue.
Thus, there remains a need in the art for improvement in artificial
tracheal implants
DESCRIPTION OF FIGURES
FIG. 1A includes a schematic representation of a cross-sectional
profile of an embodiment of fibrous implant.
FIG. 1B includes a schematic representation of the fibrous implant
of FIG. 1A.
FIG. 1C includes a schematic representation of an embodiment of a
fibrous implant.
FIG. 2A includes a schematic representation of an embodiment of a
fibrous implant having external structural reinforcing members.
FIG. 2B includes a schematic representation of an embodiment of a
fibrous implant having sharp interfaces between different fiber
types.
FIG. 2C includes a schematic representation of an embodiment of a
fibrous implant having gradient interfaces between different fiber
types.
FIG. 3 includes an image of fibers associated with a structural
reinforcing member.
FIGS. 4A-4D include micrographs of tissue with respect to a fibrous
implant.
FIG. 5 illustrates a method of forming a fibrous implant patch from
a tubular fibrous implant.
FIG. 6A includes an image of aligned fibers of a fibrous implant
patch.
FIG. 6B includes an image of a fibrous implant patch of FIG. 6A
implanted into a tracheal defect.
FIG. 7A includes a 3D rendering from microCT analysis of a fibrous
implant patch after six weeks in a rabbit trachea (anterior
view).
FIG. 7B includes a 3D rendering from microCT analysis of a fibrous
implant patch after six weeks in a rabbit trachea (lumen view).
Image demonstrates patch's ability to keep airway open.
FIG. 7C includes a photographic image of fibrous implant patch
after six weeks in a rabbit trachea.
DETAILED DESCRIPTION
In the following detailed description, reference is made to the
accompanying drawings, which form a part hereof. In the drawings,
similar symbols typically identify similar components, unless
context dictates otherwise. The illustrative embodiments described
in the detailed description, drawings, and claims are not meant to
be limiting. Other embodiments may be utilized, and other changes
may be made, without departing from the spirit or scope of the
subject matter presented herein. It will be readily understood that
the aspects of the present disclosure, as generally described
herein, and illustrated in the figures, can be arranged,
substituted, combined, separated, and designed in a wide variety of
different configurations, all of which are explicitly contemplated
herein.
Generally, the present invention includes fibrous biomaterial
compositions that are prepared with or without mechanical
reinforcement and that are suitable for use as implants. The
implants can be configured for tissue regeneration and repair as
well as for other uses. The implants can include biocompatible
fibers arranged in a manner that facilitates implantation in order
to promote biocompatibility as well as cell or extracellular matrix
ingrowth into the implant between the fibers or to replace degraded
fibers. The implant can have aligned fibers to random fibers, and
can be configured for short or long term use, such as by being
biostable or biodegradable. The overall implant or individual
fibers can include or be devoid of polymeric coating compositions
over a structural core or thread or ribbon. The individual fibers
can be cylindrical polymers with regular or irregular
cross-sectional profiles. The individual fibers can include active
agents, such as antimicrobials or pharmaceuticals or tissue growth
factors. The fibers and fibrous implant can be configured
particularly for tracheal application, such as being arranged
together for use as a tracheal implant. The fibrous implant may
also be configured as other types of implants in other
applications, such as esophageal, intestinal, arterial, or other
body lumen or patch for a body lumen or tissue patch.
In one embodiment, the individual fibers can have a uniform
composition. For example, the fiber can be prepared from a
biocompatible material (e.g., biostable or biodegradable), such as
a polymer, metal, ceramic, glass, bioglass (e.g., biodegradable)
composite, alloy, or combination thereof.
In one embodiment, the individual fibers can be solid and uniform,
or have a core and shell cross-sectional profile. When uniform, the
fibers can have any of the properties described for a core and/or
shell. The core can be a structural material that provides shape
and structural properties to the fiber. The core can be flexibly
resilient, deformable, or rigid. The core can be modified to have
properties as desired so that the implant can range from being
malleable or deformable or bendable to shape-set or rigid. The core
can be a polymer, metal, ceramic, glass, composite, alloy, or
combination thereof, which is harder or more rigid or more
structurally sound compared to the shell. The core can also include
bioactive agents as described herein. The shell can be a polymeric
material that is commonly used for biomedical applications on
implants. The polymeric shell can encapsulate the core. The
polymeric shell can also include bioactive agents as described
herein. The shell can be a polymer, metal, ceramic, glass,
composite, alloy, or combination thereof, which is softer or less
rigid or more structurally sound compared to the shell.
The individual fibers can be prepared from polymeric scaffold
materials, such as materials that can be based on polymeric
electrospun fibers (e.g. polycaprolactone, or
poly(lactic-co-glycolic acid) that are fabricated to form an
implant in a graded-manner (i.e., gradual transition between two
polymeric layers) using a co-electrospinning technique. Other
examples of polymers that can be used for the fibers and implant
can include synthetic rubber, Bakelite, neoprene, nylon, PVC,
polystyrene, polyethylene, polyetheylene oxide, poly(ethylene
terephthalate), polylactate, polylactic acid, polyglyconate,
polyglycolic acid, polypropylene, polyacrylonitrile, PVB, silicone,
polydimethylsiloxane, polyurethane, and many more including blends
or combinations of any of these polymers. The polymers can be
biodegradable or biostable. The individual fibers or overall
implant can include bioactive material components (e.g., bioactive
glass strips), nanophase materials (e.g., chondroitin sulfate), or
proteins (e.g., growth factors like transforming growth factor beta
(TGF-beta) and epidermal growth factor (EGF)) as well as any
well-known component of a composition for implantation.
The fibrous implant can be shaped into various forms (e.g.,
tubular, sheets, patches). The fibrous implant can include shapes
that are solid through their core as well as hollow or luminal,
where the cross sectional profiles can include triangles, squares,
rectangles, rhombus, trapezoidal, and any other polygonal shape as
well as circular or oval shapes or combinations of polygons with
circular features.
The implant can be prepared from one type of fiber. Alternatively,
the implant can be prepared from two or more types of fibers. The
fibers can be arranged to have one type of fiber at one end or on
one side, and then have a different type of fiber on the other end
or other side. The implant can include one or more different types
of fibers between the first end and other end. Any number of
different types of fibers can be used. The different fibers can be
arranged with a sharp interface therebetween with one type of fiber
on one side of the sharp interface and a different type of fiber on
the other side of the interface. Alternatively, the interface can
be a gradient interface with corresponding gradients of the
different types of fibers. In one aspect, the implant can have a
first discrete portion with a first type of fiber and a second
discrete portion adjacent to the first discrete portion with a
sharp interface therebetween and where the second discrete portion
has a second type of fiber. Optionally, the first discrete portion
can be devoid of the second type of fiber, and/or the second
discrete portion can be devoid of the first type of fiber.
Alternatively, the first and second discrete portions can have
gradients of both types of fiber. In one aspect, the implant can
have two or more types of fibers where the fibers are arranged in a
gradient from one end to the other. That is, a fiber of a first
type can be on one side of the implant with a fiber of a second
type being on the opposite side of the implant such that a gradient
of the different types of fibers exists between the two ends.
Various gradients from one end or one side to an opposite end or
side can be prepared with different types of fibers. The gradient
can be linear, curved, arcuate, or parabolic.
In one embodiment, the fibers can be arranged in a manner where
fibers having a first characteristic are at a higher concentration
or amount at one side or end of the implant and a lower
concentration or amount at the other side or end of the implant so
as to form a gradient. The fiber gradient can be constant,
variable, parabolic, or the like. The fiber gradient may also be
from one portion within the implant to another portion within the
implant or to a side or end of the implant. For example, the fiber
gradient can be from one side or end to an internal portion of the
implant, such as a middle portion or center of the implant (e.g.,
at a support member). A fiber gradient may also be designed from
one surface or end to a middle portion and then a different or same
type of fiber gradient to the opposite side or end, which can be
exemplified as a parabolic gradient. There may also be more than
one fiber characteristic with a gradient distribution from one side
or end to an opposite side or end. The fiber gradients can be from
different types of fibers with different mechanical or chemical
characteristics. The different characteristics can be the presence
or absence of active agents in fibers to form one or more active
agent gradients in the implant. Instead of having a hard or sharp
interface between fiber groups with different characteristics, the
different fibers can be arranged in a gradual or gradient interface
between them so that the fibers with different characteristics are
present in a gradient distribution. The materials of the different
fibers may also be different, which can result in different
degradation rates or active agent release rates from the fiber
materials.
In one embodiment, the implant having the fibers can have a
cross-sectional profile that includes the combined cross-sectional
profiles of the individual fibers. That is, the fibers can be
aligned so that the cross-sectional profile of the implant bisects
the individual fibers. The individual fibers can be arranged or
aligned as described herein. Also, the individual fibers can be
arranged in the implant in the manner, gradients, or other patterns
described in application Ser. No. 12/248,530 (hereinafter, the '530
application) for microspheres, which is incorporated herein by
specific reference in its entirety. That is, the fibers can be
arranged to provide the implant with a cross-sectional profile
according to the implants of the '530, where the fibers replace the
microparticles from one side to another side of the implant such as
described in any of FIGS. 2A-2D, 4A, 6A-6D, 7A-7C, or combinations
thereof. The fibers can be melded as described in the '530
application. Here, each fiber can extend from one end to another,
where the fibers are arranged in the gradient from one side to an
opposite side. The fibers may also be circumferentially aligned so
that the same fiber encircles the implant one or a plurality of
times.
The implant can be configured to be a functional tissue engineered
scaffold that harnesses gradient scaffold design and drug delivery
for tissue repair. One exemplary use described herein includes
using the implant having the fibers for tracheal defect repair,
where the fibers can be arranged circumferentially or in the
direction of collagen fibers of the trachea. The implant can be
pre-shaped or shaped in the operating room. The implant can be
prepared in various sizes to accommodate patients from fetal to
large adult sizes as well as for various sizes of defects or
tracheal holes that may form or be formed in the trachea. The
implant can be of a shape and dimension to be sufficient to be
placed into and fill a void in tracheal tissue. For example, a
surgeon can cut out the desired shape by a scalpel to provide a
custom shape, or a cookie-cutter type cutting device can be pressed
into the implant to provide a pre-determined shape. The surgeon can
then suture or otherwise implant the shaped implant to the trachea
in order to patch the tracheal defect. Alternatively, an adhesive,
such as a wound glue adhesive, can be used to adhere the implant to
the trachea.
In one embodiment, the implant can use biomaterials formed into a
biocompatible scaffold that does not use any donor tissue. The
implant can be manufactured at an industrial scale that provides a
deliverable end product with a fiber gradient that provides a
gradient of growth factors of a gradient of material composition.
The implant can be structurally self-supportive by the fibers or it
can be prepared to have some structural component that reinforces
the scaffold to provide the appropriate mechanical integrity to
keep the airway from closing. The individual fibers can include a
structural reinforcement member, such as a core, shell, edge, or
linear filament member. The individual fibers may also be
electrospun into an implant around or encapsulating a structurally
reinforcing member that is retained within the implant. For
example, a tube member of a certain material can be used for
structure, and the fibers can be electrospun around the tube
member, such as on the luminal wall and outer wall of the tube so
that the entire tube member is encapsulated by electrospun
fibers.
Preliminary studies have shown that rabbits survived and grew new
tissue over polycaprolactone (PCL) electrospun scaffolds that were
used to patch a trachea defect. Another implant may include a
faster degrading alternative to PCL. Also, gradients of fast and
slow degrading materials can be from side to side or from a side to
the middle of the implant. The electrospun fiber gradient can be
configured to allow greater tissue in-growth, while not
compromising the mechanical stability of the construct. This is
achieved by incorporating faster degrading polymers like
poly(lactic-co-glycolic acid) (PLGA) into the PCL using a
coelectrospinning process (e.g., using two or more syringes and
power supplies) to create multicomponent fibrous scaffolds.
Some exemplary novel and beneficial features of embodiments of the
fibrous implant include: the scaffolding material includes aligned
fibers (e.g., aligned electrospun fibers); the microenvironment of
the fibrous scaffold mimics native extracellular matrix (ECM) and
supports cell attachment, differentiation, and growth; and
circumferentially aligned fibers mimic the collagen in native
tracheal cartilage, where the outer superficial zones of cartilage
have circumferentially aligned collagen fibers (which are active in
tensile resistance). As such, the implant can be configured to
function as a native tracheal segment with the fibers aligned
similar to the collagen fibers of the trachea. The fibers of the
implant may also include collagen coatings for enhanced
biocompatibility. Collagen fibers may also be used. Also, the
method of manufacturing can include electrospinning the fibers,
which can be adapted to provide for a tracheal implant having
circumferentially aligned fibers, or aligned in any manner.
While the present invention has been described as being
manufactured by electrospun fibers, other manufacturing methods can
be employed. For example, the individual fibers can be extruded and
bound at their ends to form an implant. Also, individual fibers can
be aligned and then coupled together at their ends and/or one or
more discrete locations along the aligned fibers. Extruded or
molded fibers may also be encapsulated in a polymeric coating.
Other manufacturing techniques may also be suitable for forming the
fibrous.
In one embodiment, the fibrous implant can include a plurality of
fibers in a multilayer, gradient design that simulates the
epithelium and cartilage layers in the trachea. That is, the
implant can include fibers aligned to simulate the epithelium and
fibers aligned to simulate the cartilage with a suitable interface
or gradient therebetween. In each layer or in each fiber of each
layer, specific polymers and bioactive components can be tailored
to meet the specific regeneration requirements of the tissue. For
example, PLGA can be used in the outer electrospun layers as the
faster degrading layer to allow for cells to colonize the scaffold;
while PCL, a slower degrading polymer, can be used in inner layers
of the scaffold to maintain structural integrity. Fibers or support
members having biodegradable glass or other biocompatible material
can be at a middle or center portion of the implant.
In one embodiment, the fibrous implant can include a structural
reinforcing member along with the fibers to provide for further
mechanical stability in the scaffold. For example, the implant can
include one or more bioactive glass strips that are sufficient to
withstand the tracheal compressive and tensile forces and prevent
against tracheal collapse. The bioactive glass strips can be
arranged circumferentially, longitudinally, diagonally, helically,
and/or be distributed evenly or randomly through the scaffold. The
bioactive glass strips can be distributed and arranged so as to
mimic the native cartilage rings. Also, the bioactive glass can be
tubular or annularly arranged with a circumference that matches the
trachea.
The implant can be used in cell culture to grow suitable cells
prior to implantation. The implant having cells or cell cultures
attached thereto can then be implanted into a subject. Accordingly,
the implant can be used with or without cells, and does not require
specialized surgical techniques or highly invasive, multistage
surgeries. This straightforward, highly adaptable, patient-specific
approach for a tracheal implant can benefit medical practitioners
and patients.
While the present implant having fibers (e.g., in a gradient
configuration) has been described for use in tracheal defect
repair, the implant may also be dimensioned, shaped, or otherwise
configured for implantation in other tissue engineering
applications (e.g., vascular tissue engineering), or possibly even
wound or tissue regeneration (e.g., skin, liver, etc.). Thus, the
technology of the fibrous implant is not limited in its focus, and
can be configured for any implant application. The fibrous implant
can be configured for use in patch tracheal defects and whole
circumferential defects, and thereby can be used as any patch or
for any body lumen. For example, non-reinforced implants may be
used for tracheal patches while reinforced implants can be used for
circumferential implants. The device can be enhanced in mechanical
performance by incorporating resilient materials such as bioactive
glass strips, sheets, or tubes, which serve to keep the biomaterial
structurally stable (i.e., prevent collapse).
In one embodiment, computer modeling can be used to design an
implant having a gradient in one or more characteristics. The
computer model can receive experimental or theoretical data and
design an implant that is suitable for the intended use. The
computer model can determine the best way to assemble the gradient
of fibers and when and where to include one or more bioactive or
structural materials in the fibers. The computer can then control
the electrospinning in order to prepare the fibrous implant. The
computer can be programafig.med to prepare the implant with certain
characteristics. Also, the computer can receive data of a subject
in need of an implant, and then determine the structure and fibers
and fiber gradients or sharp interfaces for the implant to match a
defect to be treated with the implant.
The fibrous implant can be provided in a generic shape, and then a
medical professional can pre-shape the implant before an operation,
or easily create custom shapes during surgery. Pre-shaped fibrous
implants can also be tailored and customized before implantation.
The generic shape can be a tube similar in size and configuration
to a trachea. The fibers of the implant can extend from one end of
the tube to the other end of the tube or be circumferentially
aligned or wound. The fibers can be wound circumferentially similar
to thread wound on a spool. The body of the fibers can
cooperatively form the luminal surface and outer surface of the
tubular generic shape. The implant can be sutured in place and/or
placed with a bioadhesive, or any other method of implantation and
securement commonly used for implants can be used.
FIGS. 1A-1B illustrate an embodiment of a fibrous implant 100 in
accordance with the principles described herein. The fibrous
implant 100 is shown to have a tubular body 110 with a lumen 112.
The tubular body 110 extends from a luminal wall 114 to an outer
wall 116. The tubular body 110 can also be considered to have one
side 118 and an opposite side 120. The tubular body 110 has a first
end 122 and an opposite second end 124. As shown in FIG. 1A, the
tubular body 110 is pointing out from the page with the first end
122 being viewable. The individual fibers 150 can be wound
circumferentially from the first end 122 to the second end 124 and
back, depending on the layer, as shown in FIG. 1B. FIG. 1A shows
the fibers 150 to be arranged around a support member 126. However,
the support member 126 can be optional. The tubular body 110 is
shown to have a first annular section 102 extending from the outer
wall 116 to the support member 126 and a second section 104
extending from the support member 126 to the luminal wall 114.
The first section 102 can be prepared from one or more different
types of fibers. For example, the first section 102 can have a
first type of fiber 128 adjacent to the outer wall 116 and a second
type of fiber 130 adjacent to the support member 126. The interface
136 between the first type of fiber 128 and second type of fiber
130 can be a hard interface or a gradient interface. In the
gradient interface 136, the first type of fibers 128 can fade into
the second type of fibers 130, and vice versa. As such, the outer
wall 116 can be mostly or all the first type of fibers 128 and
adjacent to the support member 126 can be mostly or all second type
of fibers 130. Also, the second section 104 can be prepared from
one or more different types of fibers. For example, the second
section 104 can have a third type of fiber 132 adjacent to the
support member 126 and a fourth type of fiber 134 adjacent to the
luminal wall 114. The interface 138 between the third type of fiber
132 and fourth type of fiber 134 can be a hard interface or a
gradient interface. In the gradient interface 138, the third type
of fibers 132 can fade into the second type of fibers 134, and vice
versa. As such, the luminal wall 114 can be mostly or all the
fourth type of fibers 134 and adjacent to the support member 126
can be mostly or all third type of fibers 132.
In one aspect, the first type of fiber 128 and fourth type of fiber
134 can be the same; however, they can be different. In one aspect,
the second type of fiber 130 and third type of fiber 132 can be the
same; however, they can be different. In one aspect, the first type
of fiber 128 and third type of fiber 132 can be the same; however,
they can be different. In one aspect, the second type of fiber 130
and fourth type of fiber 134 can be the same; however, they can be
different. Other permutations of fiber distributions can also be
used.
The support member 126 can be an annular member, tubular member, or
it can be a "C" shape or other suitable shape, such as a helix,
spiral, or the like. The support member 126 can be a single piece
or multiple pieces, as shown in FIG. 2A below. The support member
126 can be on the luminal wall 114 or outer wall 116 instead of
being embedded within the fibers 150. The support member 126 can be
a plurality of rigid fibers aligned with the other fibers 150. The
support member 126 can be omitted, such as when one or more of the
fibers 150 or fiber types are sufficient for structural integrity
for use as an implant. Such structural integrity can be sufficient
for being used as a tracheal implant.
While the fibrous implant 100 is shown to be tubular, any other
shape can be used. The fibrous implant 100 can be solid or hollow.
The fibrous implant 100 can have a cross-sectional profile that is
circular, triangle, square, rectangular, or other polygon shape
that is hollow with a lumen or solid without a lumen. In one
embodiment, the fibrous body can have the shape of a tube, sheet,
"C", diamond, rounded diamond, polygon, circular, or oval shape or
irregular shape. In one aspect, the fibrous body can have an
irregular shape designed to conform to a correspondingly shaped
tracheal defect. The fibrous body can have a predefined shape. In
one aspect, the fibrous body is sized for a fetus or infant or
child to adolescent or teen or young adult or small adult or
average male or female adult or large adult or an animal. Fibrous
composition can be prepared as any type of implant in any shape
that is suitable to be prepared from fibers. A coating can be
applied to the outside of the implant to contain the fibers
therein. Also, the fibers can be adhered together. Additionally,
the fibers can be melded together with a solvent. In any event, the
fibers can be bound together to form a three-dimensional implant.
The fiber gradient can be with respect to the inner wall 114 and/or
outer wall 116 or support member 126. The fiber gradient can be
with respect to the first side 118 or second side 120. The fiber
gradient can be with respect to the first end 122 or second end
124.
In FIGS. 1A-1B, one of the polymers can be PLGA while the other is
PCL. For example, the fibers adjacent to the lumen or outside can
be PLGA while the fibers adjacent to the support member can be PCL.
The support member can be a bioactive glass ribbon.
FIG. 1C shows a fibrous implant 160 in the form of a solid
three-dimensional block 162. The block 162 can have a first side
164 and an opposite second side 166, and have a top side 168 and
opposite bottom side 170. The fibers 150 can extend from a first
end 172 to opposite second end 174. The fibers 150 can have first
fiber ends 152 and opposite second fiber ends 154. The block 162
can have the fibers 150 arranged with a first type of fiber 150a at
the first side 164, where the first type of fibers 150a form a
first portion 176. The block 162 can have the fibers 150 arranged
with a second type of fiber 150b at the second side 166, where the
second type of fibers 150b form a second portion 180. A third
portion 178 is positioned between the first portion 176 and second
portion 180. The third portion 178 can include a third type of
fiber or it can be a gradient distribution of the first type of
fiber 150a and second type of fiber 150b. For example, in the third
portion 178, the first type of fiber 150a can have a higher
concentration adjacent to the first portion 176 and lower
concentration adjacent to the second portion 180, and the second
type of fiber 150b can have a higher concentration adjacent to the
second portion 180 and lower concentration adjacent to the first
portion 176.
FIG. 2A illustrates another embodiment of a fibrous implant 200
with a tubular body 210 with a lumen 212, which has a support
member 226 on the outer wall 216. While five different support
members 226 are shown, any number can be used, and positioned at
any location with gaps 206 or adjacent or touching. The tubular
body 210 can include a first section 208a, second section, 208b,
and third section 208c, each section having a different type of
fiber, or the second section 208b can be a blend of the fibers of
the first section 208a and the third section 208c. The support
member 226 can be an annular member, or it can be a "C" shape or
other suitable shape, such as a spiral, or the like. The support
member 226 can be bioactive glass ribbons, which can have a
rectangular cross section, be long and straight, and be capable of
springing back to being straight if bent and released. The support
member 226 can be about 800 .mu.m wide (e.g., or +/1 5%, 10%, or
20%), 100 .mu.m thick (e.g., or +/1 5%, 10%, or 20%), and vary in
length (e.g., 8-10 cm) (e.g., or +/1 5%, 10%, or 20%). To mimic the
rabbit trachea, where cartilage rings are very narrow (.about.1 mm)
and closely spaced (.about.1 mm in between), the support member 226
ribbons can be spaced 1 mm apart from each other along the length.
The ribbons can be wrapped around the construct and secured with
liquid PCL solution (see FIG. 3).
FIG. 2B shows a portion of an embodiment of the fibrous implant 200
that can be used. The fibrous implant 200 is shown to have an inner
wall 214 and outer wall 216. The fibrous implant 200 is shown to
have a first section 202 extending from the outer wall 216 to the
support member 226 and a second section 204 extending from the
support member 226 to the inner wall 214. The first section 202 can
have a first type of fiber 228 adjacent to the outer wall 216 and a
second type of fiber 230 adjacent to the support member 226. The
interface 236 between the first type of fiber 228 and second type
of fiber 230 is a sharp interface, such that there is substantially
none of the first type of fiber 228 mixed with the second type of
fiber 230. Also, the second section 204 can have a third type of
fiber 232 adjacent to the support member 226 and a fourth type of
fiber 234 adjacent to the inner wall 214. The interface 238 between
the third type of fiber 232 and fourth type of fiber 234 is a sharp
interface, such that there is substantially none of the third type
of fiber 232 mixed with the fourth type of fiber 234.
FIG. 2C shows a portion of another embodiment of the fibrous
implant 200 that can be used. The fibrous implant 200 is shown to
have an inner wall 214 and outer wall 216. The fibrous implant 200
is shown to have a first section 202 extending from the outer wall
216 to the support member 226 and a second section 204 extending
from the support member 226 to the inner wall 214. The first
section 202 can have a first type of fiber 228 adjacent to the
outer wall 216 and a second type of fiber 230 adjacent to the
support member 226. A gradient interface 240 is located between the
first type of fiber 228 and second type of fiber 230 such that
there is first type of fiber 228 mixed with the second type of
fiber 230 in gradients. Also, the second section 204 can have a
third type of fiber 232 adjacent to the support member 226 and a
fourth type of fiber 234 adjacent to the inner wall 214. A gradient
interface 242 is located between the third type of fiber 232 and
fourth type of fiber 234 such that there is third type of fiber 232
mixed with the fourth type of fiber 234 in gradients. The gradients
can be linear or curved as shown in the '530 Application.
The fibrous body can include one or more different types of fibers,
such as at least two different types of fibers, or a plurality of
different types of fibers that are aligned in the same direction.
The fibrous body can have a first type of fiber having a first
characteristic in a first gradient distribution across at least a
portion of the fibrous body. A second type of fiber can have a
second characteristic in a second gradient, which second gradient
can be opposite of the first gradient. The different
characteristics an include type of composition; type of polymer;
fiber diameter size; fiber diameter size distribution; type of
bioactive agent in a fiber; type of bioactive agent combination in
a fiber; bioactive agent concentration in a fiber; amount of
bioactive agent in a fiber, rate of bioactive agent release from a
fiber; mechanical strength of a fiber; flexibility of a fiber;
rigidity of a fiber; color of a fiber; radiotranslucency of a
fiber; or radiopaqueness of a fiber. Some preferred examples of
different characteristics can be different fibers having different:
bioactive agents; antimicrobial agents; pharmaceuticals; structural
reinforcing members; polymer type; fiber type; cell types attached
to the fibers; fiber compositions thereof, and combinations
thereof. In one aspect, the fibrous body can include different
fibers with two or more characteristics in two or more gradient
distributions or varying gradient distributions. In one aspect, the
fibrous body can have a higher concentration of fibers having one
or more characteristics on one side or end of the body than in the
center and/or on an opposite side or end of the body. In one
aspect, the fibrous body can have a higher concentration of fibers
with one or more active agents on one side or end of the body than
in the center and/or on an opposite side or end of the body. In one
aspect, the fibrous body can have a higher concentration of fibers
with structural reinforcing members, structural reinforcing fibers,
or structural reinforcing members on one side or end of the body
than in the center and/or on an opposite side or end of the body,
or the reinforcing members can be centered or between the sides or
ends of the body. In one aspect, the fibrous body can have PCL
fibers in one gradient distribution and PLGA in another
distribution.
In one embodiment, the implant can include a plurality of fibers
forming an implant body having: a first set of fibers having a
first gradient spatial distribution with a higher concentration at
the first end and lower concentration at the second end of the
body; and a second set of fibers that are different from the first
set of fibers, the second set of fibers having a second gradient
spatial distribution with a lower concentration at the first end
and higher concentration at the second end of the body. In one
aspect, the first gradient spatial distribution and second gradient
spatial distribution blend into each other. In one aspect, the
fibrous implant can include: a first portion at the first end
having a majority of fibers of the first set; and a second portion
at the second end having a majority of fibers of the second set. In
one aspect, the fibrous implant can include: a first portion at the
first end having a majority of fibers of the first set; a second
portion at the second having a majority of fibers of the second
set; and a third portion disposed between the first portion and the
second portion, wherein the first gradient spatial distribution in
the third portion forms a first concentration gradient of the first
set of fibers and the second gradient spatial distribution in the
third portion forms a second concentration gradient of the second
set of fibers. In one aspect, the fibrous implant can include a
first bioactive agent contained in or disposed on the first set of
fibers, and the second set of fibers being substantially devoid of
the first bioactive agent. In one aspect, the fibrous implant can
include a first bioactive agent contained in or disposed on the
first set of fibers, and a second different bioactive agent
contained in or disposed on the second set of fibers. In one
aspect, the plurality of fibers include polymeric fibers or having
polymeric coatings that electrospun or melded together. In one
aspect, at least one of the first set or second set of fibers is
comprised of a biodegradable polymer, such PLGA. In one aspect, the
fibrous implant can include live cells and a medium sufficient for
growing the cells disposed in the interstitial spaces between the
fibers. In one aspect, a first bioactive agent is contained in or
disposed on the fibers of the first set, and a second different
bioactive agent is contained in or disposed on the fibers of the
second set. For example, the first bioactive agent can be an
osteogenic factor and the second bioactive agent can be a
chondrogcnic factor. In another aspect, the different fibers can
have a transforming growth factor (TGF)-.beta..sub.3 and/or of
epidermal growth factor (EGF) or keratinocyte growth factor (KGF)
or vascular endothelial growth factor (VEGF). In one aspect, the
first set of fibers have a first characteristic and are devoid of a
second different characteristic, and the second set of fibers
having the second different characteristic and are devoid of the
first characteristic.
In one embodiment, the fibrous implant can include a plurality of
live cells attached to the plurality of fibers. The cells can be
any type of animal cell, such as human cells, or even cells of the
subject to receive the fibrous implant. The fibrous implant can
include a first cell type associated with a first set of fibers,
and a different second cell type associated with a second set of
fibers.
In one embodiment, a method of preparing tissue engineering
scaffold for growing cells can be performed with the fibrous
implant. The method can include: providing a first set of fibers;
providing a second set of fibers different from the first set of
fibers; and combining (e.g., electrospinning) the fibers of the
first set and second set together so as to form a body. However,
the fibers can be prepared during the electrospinning process,
where a first composition is prepared into the first set of fibers
and a second composition is prepared into the second fibers. Some
of the fibers can be prepared so as to degrade over time. Also,
some of the fibers can be prepared so as to release the bioactive
agents to promote healing or tissue ingrowth into the fibrous
implant. Multi layered and gradient scaffolds can be fabricated
using a co-electrospinning process with two or more syringes in
programmable syringe pumps.
In one embodiment, the fibrous body can have individual fibers with
a first characteristic, wherein the fibers are arranged in a first
gradient distribution across at least a portion of the fibrous
body. In one aspect, the fibrous body can have different types of
fibers having different characteristics with a fiber with one
characteristic having a first gradient distribution with respect to
one side or end of the implant and a different fiber having a
second characteristic having a second gradient distribution with
respect to a second side or end of the implant. In one aspect, the
fibrous body can have different fibers having different
characteristics with a fiber with one characteristic having a first
gradient distribution with respect to a center point or plane of
the implant and a fiber with a second characteristic having a
second gradient distribution with respect to a side or end of the
implant. Accordingly, the fibrous body can have a plurality of
fiber layers from one side or end to another side or end. Each
fiber layer can have a different type of fiber.
In one embodiment, the fibrous body can be formed so as to have
fibers wound (e.g., substantially circumferentially) around a spool
to form a wound fibrous body. The spool can be removed to form a
tubular implant. The fibrous body can have fibers of a first type
at one or more inner layers of the wound fibrous body and fibers of
a second type at one or more layers of the wound fibrous body
adjacent to the one or more inner layers. In one aspect, the fibers
can be longitudinally aligned. Alternatively, the fibers can be
laterally aligned. The fibers can be diagonally or helically
aligned. In one aspect, the fibrous body can be formed so as to
have fibers wound around a spool to form a wound fibrous body, with
the fibrous body having: fibers of a first type at one or more
inner layers of the wound fibrous body; fibers of a second type
intermingled with the one or more inner layers of the fibers of the
first type; and fibers of the second type at one or more second
layers of the wound fibrous body adjacent to the one or more inner
layers. In one aspect, the fibrous body can be formed so as to have
fibers wound around a spool to form a wound fibrous body, with the
fibrous body having: fibers of a first type at one or more inner
layers of the wound fibrous body; fibers of a second type
intermingled with the one or more inner layers of the fibers of the
first type; fibers of the second type at one or more second layers
of the wound fibrous body adjacent to the one or more inner layers;
fibers of a third type or the first type intermingled with one or
more second layers of the fibers of the second type; and fibers of
the third type at one or more third layers of the wound fibrous
body adjacent to the one or more second layers.
In one embodiment, the fibrous body can have the fibers aligned
from top to bottom (e.g., superoinferiorly) with respect to
implantation orientation of an upright subject. In one aspect, the
fibrous body can have the fibers aligned from side to side (i.e.,
mediolaterally at the anterior aspect of the trachea; in the
transverse plane) with respect to implantation orientation of an
upright subject.
In one embodiment, the fibrous body can have void space sufficient
for culturing cells within the implant or on one or more fibers.
This can be from selective degradation of the fibers, laser etching
after formation of the fibrous body, forming pores with solvent, or
by the interstitial spaces between adjacent fibers. Also, the void
space can form over time after implantation. The void space can
include a cell culture media in in vitro application. The void
space can include cells in in vitro or in vivo applications.
In one embodiment, the fibrous body can have one or more elongate
structural members arranged at from about 0 degrees to about 90
degrees with respect to the aligned fibers, such as at about 10,
20, 30, 40, 45, 50, 60, 70, about 80 degrees. The angle can be made
with respect to a longitudinal axis of the fibrous implant, a
plurality of the fibers, direction of aligned fibers, or with
respect to a single fiber. The direction of orientation can be the
longitudinal axis of the trachea or circumferentially, and the
structural members can be angled therewith.
In one example, the fibers can be aligned and arranged so as to
mimic collagen arrangement in native tracheal cartilage. However,
the fibers can also be random, unaligned, diagonally aligned,
crisscrossed, helical, orthogonal, spun, woven, or other pattern.
In one aspect, one or more of all of the fibers can be
circumferentially aligned. In one aspect, the fibrous body can
include different types of aligned fibers arranged so as to mimic
collagen arrangement in native tracheal cartilage, where outer
superficial zones of the implant mimic cartilage and has
circumferentially aligned fibers that mimic collagen fibers. In one
aspect, the fibrous body can include different types of aligned
fibers arranged in multiple layers so as to mimic and/or promote
regeneration of epithelium and cartilage layers in the trachea. In
one aspect, one or more of all of the fibers are not aligned. In
one aspect, one or more of the fibers can run circumferentially or
laterally or longitudinally with respect to an upright position of
a subject
In one embodiment, the fibrous body can include fibers that are
active in tensile resistance. As such, a force can be applied to
opposite ends of the fibers. The fibers can be longitudinally
stretched. As a baseline comparison, mechanical studies of the
trachea have provided tensile moduli ranging from 0.3 to 14 MPa,
and circumferentially aligned electrospun PCL and PLGA fibers have
ranged from 10-45 MPa. The values can be modified when bioglass is
used as a support member.
In one embodiment, the implant can include one or more fibers that
has a core and shell cross-sectional profile. In one aspect, one or
more fibers can have a core and multiple shells cross-sectional
profile. The fibers can also be solid or a single material. The
fibers can be tubular and hollow with an internal lumen. The fibers
can have a cross-sectional profile dimension ranging from about 1
mm to about 50 mm in diameter, from about 2 mm to about 25 mm, from
about 5 mm to about 20 mm, from about 8 mm to about 15 mm, or about
12 mm in diameter.
While a fibrous implant is described herein, it should be
recognized that the implant can be a pre-implant or a generic shape
that can be modified prior to implantation. That is, a scaffold,
such as a tissue engineering scaffold for in vivo or in vitro
applications, having the fibers arranged as described herein that
is not implanted or prior to implantation can be considered to be a
fibrous implant, and the features of the fibrous implant apply to
pre-implant scaffolds as well as tissue engineering scaffolds.
In one embodiment, the fibrous implant having the features or
characteristics described herein can be manufactured. A method of
manufacturing a fibrous implant can include electrospinning fibers
so as to form the electrospun fibrous body. The fibers can be
electrospun to have a first characteristic in a first gradient
distribution. The fibers can be electrospun to have a second
characteristic in a second gradient different from the first
characteristic and/or first gradient. In one aspect, the method of
manufacture can include preparing the materials or compositions for
the electrospun fibers and/or formation of the fibers therefrom.
The method can include electrospinning an inner layer of fibers,
and electrospinning one or more layers over the inner layer.
In one embodiment, the method of manufacture can include
electrospinning the fibers around one or more structural
reinforcing members (e.g., support member). The method can include
placing circumferential structural reinforcing members around an
electrospun layer, and electrospinning a layer of fibers over the
reinforcing members. The method can include electrospinning one or
more layers of aligned fibers around one or more circumferentially
or longitudinally aligned elongate structural reinforcing members.
Also, both the fibers and structural reinforcing members can be
circumferentially orientated or longitudinally oriented. The
structural reinforcing member can be bioactive glass. The
cross-sectional dimensions of the bioactive glass reinforcing
member can range from about 2 mm to about 25 mm in diameter, from
about 5 mm to about 20 mm, from about 8 mm to about 15 mm, or about
12 mm. In one aspect, the implant can be configured with sufficient
structural reinforcement members for functionality without
collapsing or restenosis. In one aspect, the structural reinforcing
members can hold the implant in shape and provide for resiliency
for the implant to spring back to shape if deformed.
FIG. 5 illustrates a method 500 of manufacturing an implant. The
top panel shows a tubular implant 510, which can be cut 512 into a
patch 514. The tubular implant 510 can be the same as the implant
100 of FIGS. 1A-1B. The tubular implant 510 is cut along line 182
to form the body 180 of the patch 514. Here, the patch 514 is shown
to have one side 118a and an opposite side 120a, and a first end
122a and an opposite second end 124a. The first end 122a or second
end 124 can be the top or bottom of the patch 514 when
implanted.
In one embodiment, the method of manufacture can include
sterilizing the implant. Any method of sterilization can be used.
For example, alcohol or other solvent can be used for
sterilization. In another example, the implant can be subjected to
heat and/or pressure for sterilization.
In one aspect, the fibrous body can be analyzed after manufacture.
This can include analysis of the alignment pattern (e.g.,
circumferential alignment or non-alignment) of the fibers. The
analysis can be performed as known in the art or described
herein.
The fibrous implants can be configured for use as implants in any
location within the body. However, the fibrous can be especially
suitable for patch or circumferential implants for body lumens,
such as the trachea, esophagus, intestine, or the like. While
tracheal embodiments as described, the use can be applied to other
body lumens.
In one embodiment, the fibrous implant can be used in a method of
treating a tracheal defect. Such as method can include providing a
tracheal implant as described herein, and implanting the tracheal
implant into a tracheal defect in a subject. The subject can be a
human or other animal. The implant can be shaped for a tracheal
defect, and implanted into a defect in the trachea. The defect can
be a circumferential defect, and the implant can be implanted in
the circumferential tracheal defect. In one aspect, the defect can
be a hole, and the implant can be used for patching the hole
defect, such as for treating tracheal stenosis. The defect can be
natural, an injury, or surgically prepared. The implant can be used
for tracheal tissue regeneration.
In one aspect, a medical professional can custom shape the tracheal
implant to match the defect. This can include providing an implant
of any shape having fibers with any degree of alignment or random
alignment to a medical professional where the medical professional
shapes the implant prior to implantation.
The interface between the fibers and the support member can vary.
In one instance, the fibers can be bonded to the support member,
such as with melting, melding, adhesive or the like. In another
instance, the fibers can encapsulate the support member. When the
support member is bioglass, the fibers can be spun around the
bioglass for encapsulation. Also, liquid polymer, such as the same
or different polymer from the fibers, can be applied to the
bioglass and fibers to promote association by the liquid polymer
solidifying. FIG. 3 illustrates an example of an interface between
the fibers and bioglass, where the arrow shows association of the
fibers with the bioglass. FIG. 3 is an SEM image of bioglass ribbon
(bulk object) encased in PCL fibers (thin spaghetti-like fibers).
Liquid PCL was used to secured bioglass to fibers at contact points
(see arrow). As such, the bioglass strips can be encapsulated
within the fibrous sheets. The bioglass can also be encapsulated
with PLGA or other polymers.
In one embodiment, one or more fibers can have chondroitin sulfate,
while other fibers may or may not have chondroitin sulfate. The
application of chondroitin sulfate in electrospun scaffolds can be
useful.
In one embodiment, the fibers can be electrospun so as to be
circumferentially oriented to mimic the tracheal structure. The
circumferentially-oriented polymer fibers can be cut, placed, and
sutured into a defect. Rings of bioactive glass can be used to
reinforce the electrospun fiber scaffold to provide the mechanical
integrity. The implant can have a circumferential fiber structure
of the native trachea collagen from the electrospun fibers in the
circumferential orientation as well as the rings of the native
trachea mimicked by the bioactive glass ribbons also in the
circumferential orientation. The fibers can be spun to form
gradients in order to accelerate regeneration as the different
fibers of the different gradients can have different
characteristics. For example, one fiber can be configured for
regenerating cartilage-like tissue and another for regenerating
ciliated epithelium, where the different fibers fade as gradients
into each other from one side of the implant to the other. When the
implant is cylindrical or cut from a cylindrical member, the fibers
can have axial gradients from an outer surface to luminal wall, and
vice versa. The gradients can also extend from a wall to an
internal support member. The fiber gradients can provide gradient
concentrations of transforming growth factor (TGF)-.beta..sub.3
(e.g., outer wall layers) for chondrogenesis and epidermal growth
factor (EGF) (e.g., inner or luminal wall layers) for
epithelialization. The implant can be properly implanted with these
orientations of these types of fibers. In one aspect, the fibrous
implant can be seeded and/or cultured with bone marrow derived
mesenchymal stem cells (BMSCs) and/or umbilical cord mesenchymal
stromal cells (UCMSCs) or different gradients thereof. The gradient
distribution of the fibers with different growth factors provides a
release gradient so that the different growth factors are released
and present in the subject in the gradient distribution. The fibers
can be loaded with various amounts of TGF-.beta..sub.3 and/or EGF
(e.g., 0, 1, or 10 ng of growth factor per 1 mg of polymer, such as
PLGA). However, the fibrous implant can be with or without growth
factors or with or without cells.
FIG. 4A shows H&E stain for PCL only fibers, which shows cell
infiltration from both sides. FIG. 4B shows Collagen II IHC for a
trilayer scaffold without growth factors (GFs). FIG. 4C is a
microCT of a trilayer scaffold with GFs, which show the open airway
and regenerated defect (arrow). FIG. 4D shows collagen II IHC for
gradient scaffold with GFs, which shows complete coverage of
cartilage-like tissue (collagen II IHC, brown/red color--grey in
grayscale) on the outside of the PCL (black) here, and normal
ciliated epithelium lining the lumen of the scaffold in all groups.
Particularly, FIG. 4A shows the feasibility of the fibrous implant,
and shows cell infiltration with electrospun PCL scaffolds after 7
weeks. Additional studies were done for 6 weeks, which include the
data of: FIG. 4B shows the trilayer fibrous implant (e.g.,
PLGA-PCL-PLGA) scaffolds without growth factors; the trilayer
scaffolds with growth factors (TGF-.beta..sub.3 encapsulated in the
outer PLGA layer and EGF in the inner layer) in FIG. 4C; and
gradient scaffolds with growth factors in FIG. 4D. The data shows
complete coverage of cartilage-like tissue (collagen ii
immunostaining) and ciliated epithelium with the addition of PLGA
and growth factors in FIG. 4D. The microCT scans revealed
acceptable narrowing of the trachea through the grafted sections,
but not severe stenosis. From gross examination of the tracheas,
scaffolds retained their shape and no air leaks or collapse was
evident. Tissue sections revealed the presence of PCL and almost
complete resorption of PLGA, as expected. As such, the growth
factors can be released faster from the PLGA on a shorter
time-scale (e.g., about 4 weeks), and for the PLGA to be degraded
and replaced by tissue regeneration, while slower degrading PCL
(e.g., about 2 years) and bioactive glass can provide structural
support to ensure long-term success of the implant.
The fibrous scaffolds used for implantation can have varied
properties, from different fibers, such as in different
distributions or gradient distributions. The fibrous scaffolds can
be modulated in terms of mechanical integrity, porosity,
degradation profiles, and growth factor release profiles and
bioactivity. Table 1 provides some examples of variations in the
fibers and fibrous scaffold.
In one embodiment, the electrospun fibrous implant can be
substantially devoid of pores or opening from the outer wall to
luminal wall. Regarding porosity, the lower porosities associated
with aligned electrospun fibers are advantageous for tracheal
regeneration as a means to maintain an airtight scaffold.
The fibrous implant can be configured to provide desirable
contraction, agent release profiles, mechanical integrity, and/or
degradation. The variables that can be modulated can include:
fibers that include collagen, poly(L-lactide-co-caprolactone), or
other similar materials in place of or blended in with PLGA and/or
PCL, 2); modified bioactive glass composition (Table 3) or
dimensions; a fiber bilayer; growth factors adsorbed or immobilized
to the surface of the fibers, coaxially electrospun into the center
of the fibers, or growth-factor-loaded microparticles could be
encapsulated into the fibers; polymeric layer thickness can be
modified; degradation rates of the polymers can be easily altered
by changing the intrinsic viscosity (i.e., changing the molecular
weight) or by changing the lactic acid to glycolic acid ratio in
the PLGA; bioactive glass degradation rate can be controlled by
altering the composition; and excipients can be included for growth
factor stabilization, including magnesium hydroxide, sucrose,
PF-127, trehalose, polyethylene glycol, magnesium carbonate,
cyclodextrins, or the like. Table 2 shows variations of the types
of fibers, growth factors, and/or cells that can be used in the
scaffolds. Table 3 shows variations in the bioactive glass
compositions that can be used, with 13-93 being preferred with
13-93B3 being second preferred.
TABLE-US-00001 TABLE 1 Layer Material Growth Thicknesses.sctn.
Group Gradient? Factors? Glass? (mm) Single-layer PCL N/A No No PCL
= 1.0 Single-layer PCL + Glass N/A No Yes PCL = 1.0 Tri-layer No No
No PLGA/PCL/PLGA = PLGA/PCL/PLGA 0.50/1.00/0.50 Tri-layer + GFs No
Yes No PLGA/PCL/PLGA = PLGA + EGF/PCL/PLGA + TGF-.beta..sub.3
0.50/1.00/0.50 Gradient* Yes No No PLGA/gradient/PCL/gradient/PLGA
= PLGA/gradient/PCL/gradient/PLGA 0.25/0.50/0.50/0.50/0.25
Gradient* + GFs Yes Yes No PLGA/gradient/PCL/gradient/PLGA = PLGA +
EGF/gradient/PCL/ 0.25/0.50/0.50/0.50/0.25 gradient/PLGA +
TGF-.beta..sub.3 Gradient* + Glass Yes Yes Yes
PLGA/gradient/PCL/gradient/PLGA = PLGA + EGF/gradient/PCL/
0.25/0.50/0.50/0.50/0.25 gradient/PLGA + TGF-.beta..sub.3
.dagger-dbl.Mechanical testing, degradation, and porosity will be
measured only on groups with no gowth factors. .sctn.Layered
scaffolds are 2.0 mm in total thickness. Diameter of the aluminum
collecting mandrel is 5 mm. *"Gradient" refers to a gradual, linear
transition between layers, as opposed to a sharp interface.
TABLE-US-00002 TABLE 2 Factor # of levels Description of levels
Scaffold 6 PCL only Design PLGA/PCL/PLGA tri-layer PLGA/PCL/PLGA
tri-layer + growth factors PLGA/PCL/PLGA gradient + growth factors
PLGA/PCL/PLGA gradient + bioactive glass + growth factors
PLGA/PCL/PLGA gradient + bioactive glass + growth factors + CS Cell
Type 2 hBMSCs or hUCMSCs (normal or CFE enriched.sup.*)
TABLE-US-00003 TABLE 3 Glass SiO.sub.2 B.sub.2O.sub.3 Na.sub.2O
K.sub.2O MgO CaO P.sub.2O.sub.5 45S5 45.0 0 24.5 0 0 24.5 6.0
13-93* 53.0 0 6.0 12.0 5.0 20.0 4.0 13-93B1 35.33 17.67 6.0 12 0
5.0 20.0 4.0 13-93B3* 0 53.0 6.0 12.0 5.0 20.0 4.0
FIGS. 6A-6B show an embodiment of a fibrous implant (FIG. 6A) and
implantation thereof (FIG. 6B). The fibrous scaffold was fabricated
using a rotating mandrel to create circumferential alignment of
electrospun PCL fibers. A high degree of electrospun fiber
orientation can provide cell alignment in the direction of fiber
orientation. Prior to implantation, the scaffold were imaged with
SEM (FIG. 6A). The biomaterial graft was sterilized, and a
pre-sized piece was placed over an induced 11) elliptical-shaped
defect (FIG. 6B) in the anterior tracheal wall, as well as
subcutaneously. After 7 weeks, the rabbits (n=2) were euthanized
and the tracheas and subcutaneous implants were collected for
analysis. At the conclusion of the study, the tracheas were
prepared and sectioned for histological staining (H&E) after
being imaged using computer tomographic (CT) imaging. Prior to
implantation, scaffolds exhibited fiber alignment (FIG. 6A). During
the 7 weeks in vivo, the animals ate and breathed normally with no
complications. From gross examination of the tracheas after week 7,
the constructs appeared to be covered with vascularized tissue and
no air leaks or collapse were evident. The CT scans revealed slight
narrowing of the trachea through the grafted sections (FIG. 6B),
but no severe stenosis. Sections of the tissue revealed the
presence of PCL as expected, and cell infiltration into the
scaffold. Based on these preliminary results, we have established
that these scaffolds were biocompatible and were rigid enough to
keep the trachea patent. The scaffold maintained its shape and
minimal degradation of the scaffold material was observed. After
implanting manufactured PCL scaffolds into elliptical-shaped
defects in rabbit tracheas for 7 weeks, the scaffolds maintained a
robust, airtight trachea free of any breathing distress, and
exhibited evidence of cell infiltration into the scaffold and
tissue regeneration.
FIG. 7A-7C show results of fibrous implant patch in rabbit trachea
after 6 weeks. FIG. 7A includes a 3D rendering from microCT
analysis of a fibrous implant patch after six weeks in a rabbit
trachea (anterior view). FIG. 7B includes a 3D rendering from
microCT analysis of a fibrous implant patch after six weeks in a
rabbit trachea (lumen view). Image demonstrates patch's ability to
keep airway open. FIG. 7C includes a photographic image of fibrous
implant patch after six weeks in a rabbit trachea. Three
experimental groups were fabricated: trilayer
[poly(lactic-co-glycolic acid) (PLGA)-polycaprolactone (PCL)-PLGA]
scaffolds without growth factors, trilayer scaffolds with growth
factors (transforming growth factor-.beta..sub.3 encapsulated in
the outer PLGA layer and epidermal growth factor in the inner
layer), and gradient scaffolds with growth factors. The scaffolds
were fabricated using a rotating mandrel to create aligned
electrospun fibers. Prior to implantation, scaffolds were imaged
with SEM. The biomaterial grafts were sterilized, and pre-sized
pieces were placed over an induced elliptical-shaped defect in the
anterior tracheal wall of New Zealand White rabbits (two rabbits
per group, six rabbits total). After 6 weeks, the rabbits were
euthanized and the tracheas and subcutaneous implants were
collected for analysis. At the conclusion of the study, the
tracheas were prepared and sectioned for histological and
immunohistochemical staining after being imaged using microCT
imaging. During our 6 week in vivo study, the rabbits ate and
breathed normally with no complications. None of the rabbits had
any obvious stridor. The microCT scans revealed minimal narrowing
of the trachea through the grafted sections, but not severe
stenosis. From gross examination and microCT analysis of the
tracheas, scaffolds retained their shape and no air leaks or
collapse were evident (FIG. 7A-C). After implanting manufactured
scaffolds into elliptical-shaped defects in rabbit tracheas for 6
weeks, the scaffolds maintained a robust, airtight trachea allowing
the animals to be free of any breathing distress. The implanted
material exhibited evidence of cell infiltration into the scaffold,
tissue regeneration, and re-epithelialization of the lumen.
Based on the results, we have established that these fibrous
scaffolds are biocompatible and are rigid enough to keep the
trachea patent. The scaffold maintained its shape and minimal
degradation of the scaffold material was observed. Because of PCL's
slow degradation profile, a faster degrading alternative to PCL,
such as PLGA can be used to allow tissue in-growth, while not
compromising the mechanical stability of the construct. Two types
of fibers can be prepared into a scaffold having a gradient of PLGA
and PCL. The co-electrospinning process, with two or more syringes
and power supplies, can be used to create multicomponent fibrous
scaffolds.
The present disclosure is not to be limited in terms of the
particular embodiments described in this application, which are
intended as illustrations of various aspects. Many modifications
and variations can be made without departing from its spirit and
scope, as will be apparent to those skilled in the art.
Functionally equivalent methods and apparatuses within the scope of
the disclosure, in addition to those enumerated herein, will be
apparent to those skilled in the art from the foregoing
descriptions. Such modifications and variations are intended to
fall within the scope of the appended claims. The present
disclosure is to be limited only by the terms of the appended
claims, along with the full scope of equivalents to which such
claims are entitled. It is to be understood that this disclosure is
not limited to particular methods, reagents, compounds compositions
or biological systems, which can, of course, vary. It is also to be
understood that the terminology used herein is for the purpose of
describing particular embodiments only, and is not intended to be
limiting.
With respect to the use of substantially any plural and/or singular
terms herein, those having skill in the art can translate from the
plural to the singular and/or from the singular to the plural as is
appropriate to the context and/or application. The various
singular/plural permutations may be expressly set forth herein for
sake of clarity.
It will be understood by those within the art that, in general,
terms used herein, and especially in the appended claims (e.g.,
bodies of the appended claims) are generally intended as "open"
terms (e.g., the term "including" should be interpreted as
"including but not limited to," the term "having" should be
interpreted as "having at least," the term "includes" should be
interpreted as "includes but is not limited to," etc.). It will be
further understood by those within the art that if a specific
number of an introduced claim recitation is intended, such an
intent will be explicitly recited in the claim, and in the absence
of such recitation no such intent is present. For example, as an
aid to understanding, the following appended claims may contain
usage of the introductory phrases "at least one" and "one or more"
to introduce claim recitations. However, the use of such phrases
should not be construed to imply that the introduction of a claim
recitation by the indefinite articles "a" or "an" limits any
particular claim containing such introduced claim recitation to
embodiments containing only one such recitation, even when the same
claim includes the introductory phrases "one or more" or "at least
one" and indefinite articles such as "a" or "an" (e.g., "a" and/or
"an" should be interpreted to mean "at least one" or "one or
more"); the same holds true for the use of definite articles used
to introduce claim recitations. In addition, even if a specific
number of an introduced claim recitation is explicitly recited,
those skilled in the art will recognize that such recitation should
be interpreted to mean at least the recited number (e.g., the bare
recitation of "two recitations," without other modifiers, means at
least two recitations, or two or more recitations). Furthermore, in
those instances where a convention analogous to "at least one of A,
B, and C, etc." is used, in general such a construction is intended
in the sense one having skill in the art would understand the
convention (e.g., "a system having at least one of A, B, and C"
would include but not be limited to systems that have A alone, B
alone, C alone, A and B together, A and C together, B and C
together, and/or A, B, and C together, etc.). In those instances
where a convention analogous to "at least one of A, B, or C, etc."
is used, in general such a construction is intended in the sense
one having skill in the art would understand the convention (e.g.,
"a system having at least one of A, B, or C" would include but not
be limited to systems that have A alone, B alone, C alone, A and B
together, A and C together, B and C together, and/or A, B, and C
together, etc.). It will be further understood by those within the
art that virtually any disjunctive word and/or phrase presenting
two or more alternative terms, whether in the description, claims,
or drawings, should be understood to contemplate the possibilities
of including one of the terms, either of the terms, or both terms.
For example, the phrase "A or B" will be understood to include the
possibilities of "A" or "B" or "A and B."
In addition, where features or aspects of the disclosure are
described in terms of Markush groups, those skilled in the art will
recognize that the disclosure is also thereby described in terms of
any individual member or subgroup of members of the Markush
group.
As will be understood by one skilled in the art, for any and all
purposes, such as in terms of providing a written description, all
ranges disclosed herein also encompass any and all possible
subranges and combinations of subranges thereof. Any listed range
can be easily recognized as sufficiently describing and enabling
the same range being broken down into at least equal halves,
thirds, quarters, fifths, tenths, etc. As a non-limiting example,
each range discussed herein can be readily broken down into a lower
third, middle third and upper third, etc. As will also be
understood by one skilled in the art all language such as "up to,"
"at least," and the like include the number recited and refer to
ranges which can be subsequently broken down into subranges as
discussed above. Finally, as will be understood by one skilled in
the art, a range includes each individual member. Thus, for
example, a group having 1-3 cells refers to groups having 1, 2, or
3 cells. Similarly, a group having 1-5 cells refers to groups
having 1, 2, 3, 4, or 5 cells, and so forth.
From the foregoing, it will be appreciated that various embodiments
of the present disclosure have been described herein for purposes
of illustration, and that various modifications may be made without
departing from the scope and spirit of the present disclosure.
Accordingly, the various embodiments disclosed herein are not
intended to be limiting, with the true scope and spirit being
indicated by the following claims. All references recited herein
are incorporated herein by specific reference in their
entirety.
* * * * *